Device and method for the automatic exchange of reels of web material

ABSTRACT

A device for the automatic exchange of a first reel on which a first web is wound with a second reel on which a second web is wound includes a pair of supports for the reels which are movable in a direction parallel to the axis of the reels. A first retaining member is fixed to each of the supports for the leading end of the second web, with each of the first retaining members being movable with the corresponding support between a lateral waiting position and a position of alignment with a second retaining member for the trailing end of the first web. The device also includes a pressure applicator to press the trailing end of the first web against the leading end of the second web to cause the webs to be joined, and a cutter to cut the first web to form the trailing end. An element which carries the second retaining member is movable to move the trailing end of the first web away from the support for the first web and each retaining member is associated with a bearing surface which the second retaining member is made to approach. The bearing surface is aligned with and disposed before the respective first retaining member with respect to a direction of advance of a web being unwound from a corresponding reel.

DESCRIPTION TECHNICAL FIELD

The invention relates to a device for the automatic exchange of a firstreel, on which a first web fed to a rewinding machine is wound, with asecond reel on which a second web is wound, the device comprising atleast one pair of supports for the said reels, movable in a directionparallel to the axis of the said reels; a moving element carrying aretaining member for the trailing end of the said first web; andpressing means to press the trailing end of the said first web againstthe leading end of the said second web.

BACKGROUND ART

In paper converting lines, a web material is unwound from alarge-diameter reel and is fed to what is known as a rewinder, in otherwords a machine which forms, with the web material taken from the reel,a plurality of logs or rolls of smaller diameter and of length equal tothe length of the original reel. The logs are subsequently cut intosmall rolls of smaller length, such as rolls of toilet paper, kitchenpaper or similar. In some cases, two thin layers of Web material, takenfrom two separate reels, are fed to a single rewinder and are joinedtogether during the unwinding of the reels.

When the web material fed from one reel is used up, the reel has to bereplaced and the trailing end of the web material taken from the reelbecoming used up has to be joined to the leading end of the web materialwound on the new reel. Various devices have been designed to performthis operation. For example, U.S. Pat. No. 4,629,531 describes a systemin which the end of a waiting full reel is manually prepared on asuction table. When the web fed from the reel in use is becoming usedup, it is sucked up by two adjacent suction boxes and cut transverselyalong a line between the said two boxes, and the trailing edge formed inthis way is glued to the leading edge of the web material prepared onthe suction table, which for this purpose is made to oscillate towardsthe suction boxes located above it. This device is extremely complex andlabour-intensive. Moreover, it cannot be easily used in tissue paperconverting lines, because of the particular disposition that it has toassume with respect to the path of the paper.

For the automation of the operation of exchanging the reel and joiningthe trailing edge of a web becoming used up to the leading edge of a webwound on a new reel, IT-B-1213819 describes a device with an oscillatingarm carrying a suction box which, when the web material wound on a reelin use is almost used up, is made to rest on the core of the reel andsucks up the trailing edge of the web material, keeping it connected tothe rewinder. The oscillating arm is then moved away from the core ofthe reel becoming used up, while the trailing edge of the web materialremains adhering to the suction box carried by the arm. The used reel isthen replaced with a new reel, and the oscillating arm is brought intocontact with the outer cylindrical surface of the new reel, so that thetrailing edge held by the suction box is made to rest on and is pressedagainst the outermost turn of the web material wound on the new reelwhich is suitably angularly positioned. A double-sided adhesive tape,suitably prepared, is used to stick the two layers together.

This device is simple, permits rapid replacement of the reel and a rapidjoining of the two webs, and considerably reduces the intervention ofthe operator. However, it has a limitation due to the fact that the reelin use can be replaced only when it is almost completely used up. Inpractice, however, there are frequently cases in which the reel in usehas to be replaced at an intermediate point, between the start ofunwinding and the using up of the reel. This happens because the layeror web wound on the reel may have defects or breakages in any position.In this case, the reel has to be stopped, the web has to be cut, theportion having the defect has to be removed, and then the two edges ofthe web material have to be rejoined to recommence the process ofunwinding and feeding of the web material to the rewinder.

From U.S. Pat. No. 4,392,912 a device is known, for the automaticexchange of a first reel, on which a first web fed to a processingmachine is wound, with a second reel on which a second web is wound.This device is particularly designed for reels of very limited axiallength, especially for the production of cigarettes. It includes incombination: one pair of supports for said reels, movable in a directionparallel to the axis of the reels; fixed to each of said supports arespective first retaining member for the leading end of said secondweb, each of said first retaining members being movable with thecorresponding support between a lateral waiting position and a positionof alignment with a second retaining member for the trailing end of saidfirst web, said second retaining member being carried by a fixedelement. Pressing means are also provided, to press the trailing end ofthe said first web against the leading end of the said second web,causing them to be joined together. A cutting means cuts the said firstweb to form the said trailing end. Cutting and splicing are obtained bymeans of a unit which carries said pressing means and said cutting unitand is movable in a direction orthogonal to the web feeding direction. Adouble actuator is provided: the first actuator moves the unit towardsthe fixed element which is provided with a suction plate and the secondactuator moves the cutting blade into a cutting channel upstream thesuction plate.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a reel-exchangingdevice which enables a reel in use to be replaced with another at anypoint in the operating cycle, and not necessarily when the reel in useis becoming used up.

A further object of the present invention is to provide a device whichenables an empty or damaged reel to be replaced with another, thusreducing to a minimum the downtime of the converting line and avoidingthe necessity for the operator to access the interior of the equipment.

A further object of the present invention is to provide a joining devicewhich is simpler and more compact than the devices known at present.

These and other objects and advantages, which the following text willmake clear to those skilled in the art, are obtained, essentially, witha device of the type mentioned initially, in which the element carryingthe retaining member for the trailing edge is movable such as to movethe trailing edge of the first web away from the relevant support; andeach one of the retaining members which retain the leading edge of thesecond web is associated with a bearing surface which the trailing edgeretaining member is made to approach, said bearing surface being movableintegrally with the respective leading edge retaining member and beingdisposed before said retaining member with respect to the direction ofadvance of the web being unwound from the corresponding reel.

With this arrangement, when the first reel has to be replaced the movingelement supporting the means of retaining the trailing end of the firstweb is moved to grip, with the retaining member, the free trailing edgewhich is created by the cut. This operation may be performed at anymoment, regardless of the diameter of the reel in use, which may benearly used up or may be only just started or half used. This enablesthe feed to be interrupted when damage is found in the web being fed.The new reel is transferred from a waiting position, which is lateralwith respect to the line, to the operating position. Before this, thefree leading edge of the new reel has been correctly positioned on theretaining member of the leading edge of the second web. This operationmay take place outside the converting line and in darkness, in otherwords without extending the machine downtime.

Advantageously, both the retaining members may be suction members. It isalso preferable to dispose the cutting means on the moving element whichcarries the retaining member designed to grip the trailing end of thefirst web, although a solution in which the cutting means are carried byan independent member may be considered. The retaining member of thetrailing end of the web being unwound may be mounted on a moving devicefor traversing, for example a sliding unit, or on an oscillating arm,and the same may apply to the cutting means, which may be on the sameoscillating arm or on the same sliding unit as the retaining member, oron an independent oscillating arm or sliding unit.

In the preferred embodiment of the device according to the invention,the retaining member of the leading end of the second web is carried bya carriage which is movable transversely with respect to the directionof feed of the web from the said reels, the said carriage carrying twosupports for two reels, either of which may be positioned in theoperating position. However, the two supports may be disposed on twocarriages aligned with each other and connected or operated in acombined way.

Further advantageous features of the device according to the inventionare indicated in the attached claims and will be described in greaterdetail in the following text.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the description andthe attached drawing which shows possible non-restrictive practicalembodiments of the invention. In the drawing,

FIG. 1 is a side view of the reel unwinding section in a paperconverting line, with two reels in use simultaneously;

FIG. 2 is a side view of a section similar to FIG. 1, but with only onereel in use;

FIG. 3 is a schematic plan view of the converting line to which thesection shown in FIG. 1 belongs;

FIG. 4 is a transverse section through IV--IV in FIG. 3;

FIGS. 5 to 7 show the web-joining device in three successive stages ofthe joining operation; and

FIG. 8 shows an alternative embodiment of the device shown in FIGS. 5 to7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following text the joining device will be described incombination with a paper converting line, in which the application ofthis device is particularly advantageous. However, the same device mayalso be used in different converting lines, possibly with differenttypes of material, but which present similar problems in respect of thejoining of two successive webs to be fed.

FIG. 3 shows a possible configuration of a paper converting line,typical of installations producing what is known as tissue paper. Thenumber 1 indicates in a general way the section in which the initialreel or reels from the paper factory are unwound. In the example in FIG.3, two unwinding stations 1A and 1B are provided for the simultaneousunwinding of two reels, each of which consists of a layer, preferablysingle, of web material, although it is possible for each station tounwind a reel formed from two or more previously joined layers. Thelayers unwound from the stations 1A and 1B are fed in the direction ofthe arrow f to an embossing (and possibly a printing) unit indicated ina general way by 3, and from this to a rewinder indicated in a generalway by 5. The rewinder 5 rewinds the web material, consisting of two ormore layers, on a cardboard core from a hopper container 7 disposed atone side, from which the individual cores are taken by a conveyor system11 and glued, for example along the path of insertion into the rewinder.The embossing unit 3 and the rewinder 5 may be of any type and are knownin themselves. In particular, the rewinder 5 may be a rewinder of thecentral type or a surface rewinder, and possibly of the type operatingwithout a central winding core, the operating principle of the rewinderhaving no effect on the device which is the subject of the presentinvention. The rewinder could also be of the type used for thesimultaneous production of a number of rolls whose length is smallerthan the length of the initial reel. These rewinders are frequently usedfor the production of industrial rolls whose diameters are greater thanthose of conventional logs.

Two carriages 13A and 13B, only one of which will be described in thefollowing text, the other being substantially identical, are disposed inthe section 1. Each carriage 13A, 13B has a pair of supports 15X, 15Yfor corresponding reels BX, BY of wound web. The cross-section in FIG. 4shows the carriage 13A with an empty reel BX on the support 15X and anew reel BY on the support 15Y.

Each carriage 13A, 13B is formed by a pair of longitudinal members 17connected together by cross-pieces 19. The longitudinal members 17 areguided in corresponding roller guides 21 (two for each carriage 13A,13B) which are fixed to the ground. The guides 21 extend transverselyover approximately the width of the line only, so that they do not formobstructions at the sides of the line. The carriage is supported notonly by the roller guides 21 but also by two pairs of wheels 23 disposednear the ends of each carriage. As is clearly seen in FIG. 4, the wheels23 disposed at the end of the carriage not guided by the guides 21 reston the ground and transmit part of the weight of the carriage, while theother pair of wheels is substantially free of loading, since the weightof the corresponding section of the carriage is transmitted to theguides 21.

The number 25 schematically indicates a drive unit which, by means of apinion 27 engaging with a rack 29 integral with the correspondingcarriage 13, moves the carriage transversely in the direction of f13.

In the configuration shown in FIG. 3, the two webs unwound from thereels BX of the carriage 13A and BY of the carriage 13B are fed to theembossing unit 3 and the rewinder 5, the corresponding supports of thereels being aligned with the converting line 1, 3, 5. Two reels BY andBX are placed on the supports 15Y of the carriage 13A and 15X of thecarriage 13B respectively, waiting to replace the used reels. Thereplacement is carried out by the traversing of one and/or the othercarriage in the direction of f13. The replacement is not necessarilycarried out simultaneously for the two carriages 13A, 13B, but atdifferent times in most cases. By using transversely movable carriagesthe reel on the carriage may be placed in the lateral position outsidethe converting line, while the web material unwound from the reel in theoperating position is fed from the same carriage.

As may be seen in FIG. 1 in particular, the two webs NA and NB from thetwo stations 1A and 1B are run around guide rollers 31, 32, 33, 34, 35and joined to form a single web N fed to the units 3 and 5.

FIG. 2 shows the case in which the web N is unwound from a single reel.The number of reels simultaneously in use and the number of layersforming the web N fed to the rewinder 5 may vary according to the typeof product being manufactured and are irrelevant for the purposes of thepresent invention.

Each reel is unwound by means of a belt or a set of parallel belts 37.Each belt 37 is run around a system of three pulleys 39, 41, 43, atleast one of which (typically the pulley 41) is powered. The pulleys 39and 41 are carried by a corresponding oscillating arm 45, hinged aboutan axis 45A to the fixed structure S of the machine. Conversely, thepulley 43 is carried by an auxiliary arm 47, hinged at 47A to the arm45. Between the arm 45 and the auxiliary arm 47 there is interposed anelastic system 48 (shown for simplicity in FIG. 2 only) such as apneumatic cylinder and piston system, which is used to keep the belt 37in tension.

The arm 45, with the corresponding members carried by it, is suspendedby means of a cable 49 of a hoist schematically indicated by 51. Theangular position of the arm 45 is adjusted by means of the hoist 51which unwinds or rewinds the cable 49.

To unwind the reel, the arm 45 is lowered from the position shown inFIGS. 1 and 2 until the belt 37 is brought into contact with the outersurface of the reel over a sufficiently large arc, thus providing africtional force sufficient to cause the rotation of the reel andconsequently the unwinding of the web. The tension on the belt 37 isprovided by the elastic system 48. When the belt 37 (or belts 37) ismade to rotate, the reel is caused to rotate and the feeding of web fromthe reel causes a gradual reduction of the diameter of the reel, andconsequently an elongation of the elastic system 48, with the consequentoscillation of the auxiliary arm 47 which tends to compensate for theslackening of the belt due to the reduction in diameter of the reel.

When the auxiliary arm 47 has reached a predetermined angular position,which may be detected by means of a position transducer of a known type,and possibly also by a transducer of the linear type disposed on thecylinder and piston system 48, the hoist 51 is operated to elongate thecable 49 and consequently to lower the arm 45. This enables the elasticsystem 48 to be compressed again and enables the maximum tension of thebelt 37 to be recovered. The extent of the elongation of the cable 49 isfurther determined by means of a transducer which detects the angularposition of the auxiliary arm 47 or the position of the cylinder andpiston system 48. This transducer may be the one which causes the hoistto be started. It is also possible to stop the rotation of the hoist andthe elongation of the cable 49 by means of a delay unit which stops thehoist after a specified time, or by means of an encoder which determinesthe angle of rotation of the hoist and consequently the extent of theelongation of the cable.

The unwinding system described above has the advantage, as compared withconventional systems, of drastically reducing the mass which may beginto vibrate during the unwinding of the reel. In fact, the arm 45suspended by the cable 49 acts in practice as a rigid body, and does notvibrate. Any vibrations (due for example to the irregularity of thewindings of web material wound on the reel and consequently to theimperfect cylindricality of the reel) are limited to the auxiliary arm47 and the corresponding pulley 43, which are of very low mass. Thislimits both the dynamic stresses on the machine and the noise.

The same advantages are obtained by replacing the cable and hoist system49, 51 with a hydraulic cylinder and piston actuator as shown in brokenlines and indicated by the number 52 in FIGS. 1 and 2. The hydraulicactuator imparts the same rigidity to the arm 45.

Each carriage 13A, 13B is associated with a device, indicated in ageneral way by 61, which is used to join the trailing end of one web tothe leading end of a new web from a new replacement reel.

The device, indicated purely schematically in FIGS. 1 and 2, isillustrated in detail in FIGS. 5 to 7 in its different positions. Thedevice 61 has some members carried on the corresponding carriage 13A or13B, and some members carried on the fixed frame of the machine.

On the carriage 13 there is disposed a cross-piece 63, on which ismounted a section 65 defining a cutting channel or counter-blade 67,extending in the direction f13 of movement of the carriage for adistance at least equal to the transverse dimension of the web to becut. Since the carriage 13 carries two aligned reels of which one is inuse and the other is waiting, the members 63, 65, 67 and 69 may extendover the whole length of the carriage, in other words for more thantwice the axial dimension of the reel. Conversely, two aligned sets ofmembers 63, 65, 67 and 69 may be provided, one for each support, for thecorresponding reels.

Under the cross-piece 63, and at a certain distance from it, there isdisposed a first retaining suction member 69, with a permeable suctionwall 69A facing in the same direction as the opening of cutting channel67.

A pair of parallel oscillating arms 71, hinged about an axis 71A, andoperated by an actuator 73 of the cylinder and piston or equivalenttype, is fixed to the structure S of the machine. The arms 71 carry asecond retaining suction member 75, made in the form of a box-sectioncross-piece, with a permeable suction wall 75A. The box-shapedCross-piece forming the second suction member 75 is associated with ablade 77 fixed by means of a block 79 and interacting with the channelor counter-blade 67.

The second retaining suction member 75 and the corresponding blade 77may be carried by a sliding unit movable along traversing guides, ratherthan by oscillating arms 71.

The blade 77 may be a continuous or serrated blade, and may have stripsof compressible material, which press the web material against the sidesof the channel 67 during the cut, fitted along its sides. Thecompressible material forming the strips along the sides of the blademay also be made to extend to cover the blade 77 partially orcompletely.

The device also comprises a pair of pressure rollers 81, 83, the firstof which has a fixed axle coinciding with the axis 71A of theoscillating arm 71. The second pressure roller 83 is carried by a pairof brackets 85 hinged at 87 to the structure of the machine and causedto oscillate by a cylinder and piston or equivalent actuator 89.

The operation of the device 61 is as follows. During the normaloperation of the line, the web N1 is unwound from the reel and guided bya roller 91 carried by the corresponding carriage 13 and by a roller 93carried by the structure S. The web N1 is fed along a path between themembers 63, 65, 69, 83 and the members 71, 73, 75, 77, 81 of the device61. In this condition, the pressure rollers 81, 83 are in their positionof maximum separation and the blade 77 is disengaged from the channel 67(FIG. 6).

When it is necessary to replace a reel from which the web N1 is beingfed with a new reel, the converting line is stopped and the pair of arms71 is made to oscillate anticlockwise by the actuator 73 to make theblade 77 interact with the channel 67. This causes the web N1 to be cutin a position intermediate the two guide rollers 91 and 93. The trailingend or tail of the web generated by this cut is retained between thepermeable wall 75A of the second suction member 75 and the opposingsurface of the cross-piece 63. This configuration of the device 61 isshown in FIG. 5.

When a suction system which maintains a vacuum in the interior of thesecond suction member 75 is activated, the trailing end of the web N1adheres to the outer surface of the wall 75A, so that the subsequentclockwise ioscillation of the pair of arms 71 and consequently of thesecond suction member 75 moves the trailing end of the web N1 away fromthe carriage 13. The suction is maintained to if retain the trailing endof the web N1 in position until it is joined to the second web.

At this point, the carriage 13 can be traversed in the direction f13, tobring the other support, on which the new reel has been placed, next tothe converting line. The leading end of the web N2 wound on the new reelhas previously been positioned on the outer surface of the permeablesuction wall 69A of the first suction member 69 integral with thecarriage 13. A double-sided adhesive BA has also been previouslydisposed on the web N2, in a position corresponding to the cross-piece63.

FIG. 6 shows the configuration reached after the traverse of thecarriage 13.

The two webs N1 and N2 are joined at this point by making the pressureroller 83 oscillate against the pressure roller 81, and by starting theline again, as shown in FIG. 7. At least one of the two pressure rollers81, 83 is suitably powered, in such a way that, when the line isrestarted, the trailing end of the web N1 and the leading end of the webN2 pass between the pressure rollers 81 and 83 where the pressureexerted by the said rollers causes the mutual adhesion of the two websby the action of the double-sided adhesive BA applied to the web N2. Thetwo webs N1 and N2 are joined together after the pressure rollers 81,83.

FIG. 8 shows a slightly modified embodiment of the device 61. Partsidentical to those shown in FIGS. 5 to 7 are indicated by the samereference numbers.

The device shown in FIG. 8 differs from the device shown in FIGS. 5 to 7in that the webs are joined by a ply-bonding unit rather than by a pairof pressure rollers and a double-sided adhesive. For this purpose, thetwo pressure rollers 81, 83 are replaced by a cylinder 101 of steel orother suitable material, interacting with a set of wheels 103 which, atthe time of the joining of the webs, are pressed against the cylinder101 with considerable force. The surfaces of the wheels 103 are knurledor milled in a known way, which, when they are pressed against thecylinder 101, causes the fusion of the layers of paper disposed betweenthe wheels 103 and the cylinder 101. Since the wheels 103 are subjectedto stresses different from those on the pressure roller 83, a differentsupporting and operating system is provided, replacing the brackets 85and the actuator 89. The operating system for the Wheels, indicated in ageneral way by 105, may be of a type which is known and is not describedhere in greater detail.

The disposition of the wheels 103 and of the cylinder 101 may bereversed.

The joining of the webs N1, N2 by ply-bonding has certain advantagesover the use of a double-sided adhesive. In the first place, theintermediate operation of application of the double-sided adhesive tothe web material is eliminated. In the second place, since the logproduced by the rewinder 5, within which the portion of web with thejoint is located, has to be rejected, the absence of the double-sidedadhesive makes it easier to re-use the rejected log, which can bereturned directly into the beater.

The advantages mentioned above are also obtained with a different formof ply-bonding, for example continuous transverse ply-bonding across theweb. In this case, the wheels 103 are replaced with a single wheeldisposed on a carriage movable transversely over the transverse extentof the web unwound from the reel and interacting with the cylinder 101.The carriage carrying the wheel is driven by an independent motor.

From the operation of the joining device described above it is evidentthat it may come into operation at any time during the unwinding of thereel, and that its operation is not in any way dependent on the diameterof the reel at that time. This enables the feed of the web material froma reel to be interrupted even when the reel has not been completelyunwound, for example in the case of an intermediate defect or breakageof the web material, and enables the processing to continue with a newreel, while the replaced reel is moved outside the line and the operatormay work on it to eliminate the defective portion of web material and toprepare the remaining portion of the reel for another replacement.

In the preceding text, reference has always been made to a singlecarriage carrying two supports for two reels which are broughtalternately into the operating position. However, it is possible to usetwo or more carriages adjacent to each other, each being provided with asingle support for one reel only. In this case, each carriage will beprovided with a channel 67, a cross-piece 63 and a retaining suctionmember 69.

It is to be understood that the drawing shows only an example providedsolely as a practical demonstration of the invention, and that thisinvention may be varied in its forms and dispositions without departurefrom the scope of the guiding concept of the invention. Any presence ofreference numbers in the attached claims has the purpose of facilitatingthe reading of the claims with reference to the description and to thedrawing, and does not limit the scope of protection represented by theclaims.

I claim:
 1. A device for an automatic exchange of a first reel, on whicha first web to be fed to a rewinding machine is wound, with a secondreel on which a second web is wound, the device comprising:at least onepair of supports for the first reel and the second reel, movable in adirection parallel to axes of the first reel and the second reel; fixedto each of said at least one pair of supports a respective firstretaining member for a leading end of said second web, each firstretaining member being movable with a corresponding support between alateral waiting position and a position of alignment with a secondretaining member for a trailing end of said first web, said secondretaining member being carried by an element; a pressure applicator topress the trailing end of the first web against the leading end of thesecond web, causing the trailing end and the leading end to be joinedtogether; a cutter to cut the first web to form the trailing end;wherein said element carrying said second retaining member is movablesuch as to move the trailing end of the first web away from the supportfor the first web; and that each first retaining member is associatedwith a bearing surface which the second retaining member is made toapproach, said bearing surface being aligned with the respective firstretaining member and being disposed before said first retaining memberwith respect to a direction of advance of a web being unwound from acorresponding reel.
 2. The device as claimed in claim 1, characterizedin that the at least one pair of supports are disposed on a carriagemovable parallel to axes of the first reel and the second reel.
 3. Thedevice as claimed in claim 1 or 2, characterized in that the cutter iscarried by the element carrying the second retaining member.
 4. Thedevice as claimed in claim 1, characterized in that the second retainingmember and the first retaining member are suction members.
 5. The deviceas claimed in claim 1, characterized in that said bearing surface isassociated with a counter-blade or channel into which the cutterpenetrates.
 6. The device as claimed in claim 1, characterized in thatsaid pressure applicator is arranged downstream of said element carryingsaid second retaining member with respect to web feeding motion.
 7. Thedevice as claimed in claim 1, characterized in that said pressureapplicator comprises two pressure rollers which press the first web andthe second web against each other with a double-sided adhesive disposedin an area in which the trailing end of the first web overlaps theleading end of the second web.
 8. The device as claimed in claim 1,characterized in that the pressure applicator includes a ply-bondingsystem which joins the first web and the second web in the absence of anadhesive.